[12Bravo]

I would go as heavy as you can with the buffer setup and bolt and still have the rifle function reliably. You definitely do not want any OOB issues.

 

['76K20andGuns]

I got the BCA .17 (16" upper) as a complete rifle from BCA. It is a PSA PS-15 lower. My BCA has not been great so far - but I've only used Federal Hornady V-Max Poly tip and CCI TNT Jacketed Hollows.

Out of around 100 Federal rounds, 20-25 had puffed cases and/or didn't eject properly.
Out of 50 CCI, I'd say 10-15 had the same issue but noticeably less damage to the casings and they seemed to eject better. There did seem to be more carbon on the exterior of the cases, however.

The rifle did come with one mag, but please note it is nearly impossible to find standard AR style mags for 17 HMR. The included mag is from Black Dog Arms and is their .22 WMR style (only available in 10-rounds), and the only issue is that the 'spring follower' inside is plastic - and the bolt catch sits forward of the mag. When the mag is empty the bcg will slam into the 'spring follower' inside the mag rather than the bolt catch. I am not a fan of this because once the mag is removed, the bolt goes all the way to the chamber as if a round is being cycled. Essentially, the only use for the bolt catch is when you're at a range and they have you lock your bolt open.

I messed with the buffer spring a little because I noticed that sometimes the bcg does not push forward enough for the ejector to catch on a round when chambered. Only once I had the issue where it caught an ejected case while chambering another round.

Installed is a Franklin C-Binary AR-15 trigger with all the light springs, I should have tried it before the trigger change but I just assumed there would be no issue.

I will be taking it out today and can provide more updates if needed - I am thinking it is just a buffer spring issue. I'll be trying out the Federal .17 SPEER rounds and Hornady 15.5 poly tip V-Max as well.

As a newbie this thing is VERY fun and easy to shoot (when it works) and I cannot wait to get it out more.


EDIT: I did not know the .17 Mach2/HMR blow-back issue with other semi-auto firearms existed. I should note that not once did the rifle fire because the bcg hit it too hard (I know that is only one of the issues).

 

[m90a1]

I got the BCA .17 (16" upper) as a complete rifle from BCA. It is a PSA PS-15 lower. My BCA has not been great so far - but I've only used Federal Hornady V-Max Poly tip and CCI TNT Jacketed Hollows.

Out of around 100 Federal rounds, 20-25 had puffed cases and/or didn't eject properly.
Out of 50 CCI, I'd say 10-15 had the same issue but noticeably less damage to the casings and they seemed to eject better. There did seem to be more carbon on the exterior of the cases, however.

The rifle did come with one mag, but please note it is nearly impossible to find standard AR style mags for 17 HMR. The included mag is from Black Dog Arms and is their .22 WMR style (only available in 10-rounds), and the only issue is that the 'spring follower' inside is plastic - and the bolt catch sits forward of the mag. When the mag is empty the bcg will slam into the 'spring follower' inside the mag rather than the bolt catch. I am not a fan of this because once the mag is removed, the bolt goes all the way to the chamber as if a round is being cycled. Essentially, the only use for the bolt catch is when you're at a range and they have you lock your bolt open.

I messed with the buffer spring a little because I noticed that sometimes the bcg does not push forward enough for the ejector to catch on a round when chambered. Only once I had the issue where it caught an ejected case while chambering another round.

Installed is a Franklin C-Binary AR-15 trigger with all the light springs, I should have tried it before the trigger change but I just assumed there would be no issue.

I will be taking it out today and can provide more updates if needed - I am thinking it is just a buffer spring issue. I'll be trying out the Federal .17 SPEER rounds and Hornady 15.5 poly tip V-Max as well.

As a newbie this thing is VERY fun and easy to shoot (when it works) and I cannot wait to get it out more.


EDIT: I did not know the .17 Mach2/HMR blow-back issue with other semi-auto firearms existed. I should note that not once did the rifle fire because the bcg hit it too hard (I know that is only one of the issues).

If BCA is using the same buffer and spring in the .17 that they supply with the .22 Magnum, they're both too light. I have the .22 and while it does work with the supplied parts, I've found it to work much better with a heavier buffer and stronger spring. A regular AR15 carbine spring will do the job, but I found the Tubb lightweight(.300 BO) spring to be better for me. I'm running an A2 rifle stock with a 5.8 oz. rifle buffer, the Tubb spring, and a 1-1/2" Delrin spacer to limit bcg travel to the correct distance. This combination is the softest shooting .22 in my stable, including all the .22LRs. This thing works with any ammo I can find. If I get a .17, this is the setup I'm trying.

A heavier setup will probably take care of your bulged case problems. You could increase the weight of the BCA buffer to keep the carbine buffer tube by installing/changing weights. I did that originally, but wanted to run a rifle/fixed stock.

 

['76K20andGuns]

If BCA is using the same buffer and spring in the .17 that they supply with the .22 Magnum, they're both too light. I have the .22 and while it does work with the supplied parts, I've found it to work much better with a heavier buffer and stronger spring. A regular AR15 carbine spring will do the job, but I found the Tubb lightweight(.300 BO) spring to be better for me. I'm running an A2 rifle stock with a 5.8 oz. rifle buffer, the Tubb spring, and a 1-1/2" Delrin spacer to limit bcg travel to the correct distance. This combination is the softest shooting .22 in my stable, including all the .22LRs. This thing works with any ammo I can find. If I get a .17, this is the setup I'm trying.

A heavier setup will probably take care of your bulged case problems. You could increase the weight of the BCA buffer to keep the carbine buffer tube by installing/changing weights. I did that originally, but wanted to run a rifle/fixed stock.
View attachment 378116

Understood, makes sense now. I'd definitely like to keep the Carbine Buffer tube if possible, but I can change it out if required.

I do not want to point out things from other threads, but it was noted below "A BCA buffer with enough tungsten, steel and aluminum weights to make it 5.4 ounces or more, a Tubb AR15 rifle/carbine, flatwire spring, and a 2.875" Delrin spacer to limit bolt travel in an A2 rifle buffer tube".
I imagine I wouldn't use the the Delrin Spacer, seeing as I'd like to keep it carbine length? And just roll with an H3 buffer, Tubb Flatwire spring for now?

Here's the easy combination. A BCA buffer with enough tungsten, steel and aluminum weights to make it 5.4 ounces or more, a Tubb AR15 rifle/carbine, flatwire spring, and a 2.875" Delrin spacer to limit bolt travel in an A2 rifle buffer tube. The flatwire spring made considerable difference over the typical round spring. This thing shoots softer than my CMMG .22LR setup firing Aguila Interceptor.

The modified BCA buffer works no better than a regular 5.4 once H3 Carbine buffer. The spacers just have to be correct for the shorter length H3, 4.125". I actually used the carbine buffer setup to get the right combination of buffer weight, spacer length, and spring before modding the BCA buffer. Was a lot easier to use parts on hand than having to repeatedly take the BCA buffer apart to change weights.

In the end, I did replace the roll pin that holds the rubber bumper in the BCA buffer with a 6-32 set screw. Now I can change the weight without having a hammer and punch to remove the pin. See, an inveterate tinkerer.

View attachment 361346

Another thing I noticed is that the included BCA spring tends to rattle around quite a bit in the buffer tube after a shot is fired, so I am hoping replacing that spring with the flatwire will limit that.

 

[m90a1]

Understood, makes sense now. I'd definitely like to keep the Carbine Buffer tube if possible, but I can change it out if required.

I do not want to point out things from other threads, but it was noted below "A BCA buffer with enough tungsten, steel and aluminum weights to make it 5.4 ounces or more, a Tubb AR15 rifle/carbine, flatwire spring, and a 2.875" Delrin spacer to limit bolt travel in an A2 rifle buffer tube".
I imagine I wouldn't use the the Delrin Spacer, seeing as I'd like to keep it carbine length? And just roll with an H3 buffer, Tubb Flatwire spring for now?



Another thing I noticed is that the included BCA spring tends to rattle around quite a bit in the buffer tube after a shot is fired, so I am hoping replacing that spring with the flatwire will limit that.

As you can see from my various postings, I've tried several different combinations of parts trying to find the best setup. You can run the H3 buffer, but you'll still need a spacer to limit bcg travel in a carbiine tube. Put the H3 and a regular carbine spring in the tube and then rack the charging handle. You'll see that the handle is going to hit the end of the slot in the upper before the buffer bottoms out in the tube. You REALLY don't want that to happen! Limit the bcg travel to approximately 1/4" before hitting the back of the slot. The easiest way to do that is to make a spacer that is the difference in the length of the carbine buffer and the BCA buffer. Just make sure the spacer fits inside the spring, not under it.

The flatwire springs make no noise in the buffer tube.

 

['76K20andGuns]

As you can see from my various postings, I've tried several different combinations of parts trying to find the best setup. You can run the H3 buffer, but you'll still need a spacer to limit bcg travel in a carbiine tube. Put the H3 and a regular carbine spring in the tube and then rack the charging handle. You'll see that the handle is going to hit the end of the slot in the upper before the buffer bottoms out in the tube. You REALLY don't want that to happen! Limit the bcg travel to approximately 1/4" before hitting the back of the slot. The easiest way to do that is to make a spacer that is the difference in the length of the carbine buffer and the BCA buffer. Just make sure the spacer fits inside the spring, not under it.

The flatwire springs make no noise in the buffer tube.

fantastic, you will hear back from me soon thx again!

 

[gobigkahuna]

As you can see from my various postings, I've tried several different combinations of parts trying to find the best setup. You can run the H3 buffer, but you'll still need a spacer to limit bcg travel in a carbiine tube. Put the H3 and a regular carbine spring in the tube and then rack the charging handle. You'll see that the handle is going to hit the end of the slot in the upper before the buffer bottoms out in the tube. You REALLY don't want that to happen! Limit the bcg travel to approximately 1/4" before hitting the back of the slot. The easiest way to do that is to make a spacer that is the difference in the length of the carbine buffer and the BCA buffer. Just make sure the spacer fits inside the spring, not under it.

The flatwire springs make no noise in the buffer tube.

Thanks for this information. What did you make your spacer out of? I have access to a 3D printer, so I'm thinking of using PLA?

Also saw this review on Youtube:

 

[m90a1]

Thanks for this information. What did you make your spacer out of? I have access to a 3D printer, so I'm thinking of using PLA?

Also saw this review on Youtube:

I turned my spacer on a lathe out of Delrin rod. I also have some that I made out of Aluminum rod. I know nothing of the characteristics of PLA, so just make sure it can remain functional under the stress of repeated impacts from the buffer.

I just watched the video and it will be interesting to see if the heavier buffer/spring combination will alleviate the problems he had with case deformation. I believe it will. The problems could have been caused by early unlocking of the bolt when firing. I don't have a .17 HMR upper, so some of you guys will have to share your experiences.

 

[12Bravo]

I don't think I would trust PLA to stand up to the constant shock inside the buffer tube. The preferred materials for buffers is usually nylon. Delrin would work just fine for a spacer though. Delrin is harder and more brittle than nylon. When it comes to the different polymers, too soft or to hard and it just won't last long under stress.

 

['76K20andGuns]

I turned my spacer on a lathe out of Delrin rod. I also have some that I made out of Aluminum rod. I know nothing of the characteristics of PLA, so just make sure it can remain functional under the stress of repeated impacts from the buffer.

I just watched the video and it will be interesting to see if the heavier buffer/spring combination will alleviate the problems he had with case deformation. I believe it will. The problems could have been caused by early unlocking of the bolt when firing. I don't have a .17 HMR upper, so some of you guys will have to share your experiences.

Yesterday, I started off my day by learning really fast that 15.5 Grain (Lighter cartridges) will have demolished cases regardless. Image below of the 15.5... and man, I cleaned it up and checked it real good after this.

I've gotten the new spring in, and this alone made a MASSIVE difference. I went through 31 rounds before having a misfire. Of those 31 rounds, only seven (yes, 'only' 7 out of 31 is still a lot!) had misfired or blown cases. All 31 of those rounds and the 19 following were CCI .17 V-Max Poly Tips. I have yet to try 20 grain, but I really would like to.

The heavier spring was almost flawless with ejection; 4 of the misfired rounds had issues with ejection. My next step is to install the heavier buffer to help with letting ejection, as the bolt caught another three shells when cycling. The only issue is that the new buffer, per @m90a1's notes, is just a carbine length and the Buffer that BCA includes is their own custom length. I would really like to be able to add weights to the BCA buffer to eliminate the need for spacers, but that is for another time.

Thanks for this information. What did you make your spacer out of? I have access to a 3D printer, so I'm thinking of using PLA?

Also saw this review on Youtube:

I would not use PLA, some sort of high density nylon is the softest I'd go. I feel like PLA would separate with time/use, and any heat that happens to get trapped will not help that. I'll use Delrin, Aluminum or Steel, I know I'll be seating 3/8" to 1/4" of my spacer behind the spring, and the remainder necked down to sit inside the spring with a decent chamfer as a 'spring guide'*. My goal is that not only will it hold the spacer without interfering with the spring, but also that my spring retains as much travel as possible. The bolt was not even doing full travel sometimes with the new spring, so limiting that more only means more spring tension.
*Specifically, 1/4" behind spring and 7/8" inside spring for Delrin / 3/8" behind spring and 1" inside spring for Aluminum/Steel



I know this is just me spewing things, so others should jump in with corrections, ideas and opinions!

 

['76K20andGuns]

Yesterday, I started off my day by learning really fast that 15.5 Grain (Lighter cartridges) will have demolished cases regardless. Image below of the 15.5... and man, I cleaned it up and checked it real good after this.
View attachment 380762


I've gotten the new spring in, and this alone made a MASSIVE difference. I went through 31 rounds before having a misfire. Of those 31 rounds, only seven (yes, 'only' 7 out of 31 is still a lot!) had misfired or blown cases. All 31 of those rounds and the 19 following were CCI .17 V-Max Poly Tips. I have yet to try 20 grain, but I really would like to.

The heavier spring was almost flawless with ejection; 4 of the misfired rounds had issues with ejection. My next step is to install the heavier buffer to help with letting ejection, as the bolt caught another three shells when cycling. The only issue is that the new buffer, per @m90a1's notes, is just a carbine length and the Buffer that BCA includes is their own custom length. I would really like to be able to add weights to the BCA buffer to eliminate the need for spacers, but that is for another time.




I would not use PLA, some sort of high density nylon is the softest I'd go. I feel like PLA would separate with time/use, and any heat that happens to get trapped will not help that. I'll use Delrin, Aluminum or Steel, I know I'll be seating 3/8" to 1/4" of my spacer behind the spring, and the remainder necked down to sit inside the spring with a decent chamfer as a 'spring guide'*. My goal is that not only will it hold the spacer without interfering with the spring, but also that my spring retains as much travel as possible. The bolt was not even doing full travel sometimes with the new spring, so limiting that more only means more spring tension.
*Specifically, 1/4" behind spring and 7/8" inside spring for Delrin / 3/8" behind spring and 1" inside spring for Aluminum/Steel



I know this is just me spewing things, so others should jump in with corrections, ideas and opinions!

EDIT: I'm not a great shot, but all but four holes in the target below were at 100 yards (The larger holes are a .308 AR-10). Happy to post a new thread once issues are sorted with my little build.

 

[m90a1]

*Specifically, 1/4" behind spring and 7/8" inside spring for Delrin / 3/8" behind spring and 1" inside spring for Aluminum/Steel
I know this is just me spewing things, so others should jump in with corrections, ideas and opinions!

You'll need only 1/16" of the spacer under the spring no matter which material you use. Anything more will only increase spring pressure that isn't needed.

 

[12Bravo]

If BCA would have went with a delayed blow back system like what Savage uses in their A17 series rifles, then you all would not be having issues or have to play with spring weights, buffer weights, and shims.

Years ago people who bought semi autos chambered in 17m2 and 17HMR by other manufacturers went through the same things. And this is why most manufacturers gave up on semi auto 17m2 and 17HMR rifles. The pressure curves of 17m2 and 17HMR are a lot different than 22LR and 22WMR which makes the 17 caliber semi auto rifles harder to get running reliably without any OOB issues, case ruptures, or extraction issues

I wish all of you that bought the BCA 17HMR upper the best of luck with them. But as a left handed shooter I will never shoot or own one.

 

[9x19]

You can add weights to the BCA-issued buffer, I used 3 steel and one tungsten in each of mine. I use them with a standard carbine spring. I have two pistol (SBR) uppers in .22WMR and carbine uppers in .17HMR and .22WMR.

 

[gobigkahuna]

I just got my BCA .17 HMR upper (20" stainless steel). Just waiting on some ammo I ordered. Took a photo of the included buffer & spring (top) compared to what was in my lower.

 

[m90a1]

That's the same buffer and spring that BCA supplies with the .22 Magnum conversion. Both are too light for the .22 and are assuredly too light for the .17. I will admit that the supplied pieces did work with the .22, with only occasional bulging of the brass, but worked much better with different parts

Let us know your experience when you've done some shooting.

 

[gobigkahuna]

Both the upper and some ammo arrived this afternoon. I cleaned the bore with two wet patches (Ballistol) and two dry patches. I mated it to a PSA lower, then mounted a scope and pic rail for a bipod, then shot 40 rounds in my backyard range (50 yds). I spent about 10 rounds adjusting the scope and then 10 rounds each with CCI, Remmington, and Hornady 17 grain ammo. I hadn't planned on shooting for accuracy, but even with 15-25 mph wind from my 4-6 o'clock, I had single hole groups with all three ammos. Not a single hiccup or cycling issue. After I was done I collected my brass and inspected each and every one. I didn't find any split necks, and out of 40 casings I found 5 that had puffed ends: 2 Remmingtons, 2 Hornady's and 1 CCI. I would say that the only thing I didn't like was the "boing" noise from the buffer spring. I think with a lighter trigger this thing could be my most accurate rifle.

 

[m90a1]

Just out of curiosity, how far were the fired casings being ejected?

 

[gobigkahuna]

Just out of curiosity, how far were the fired casings being ejected?

I couldn't say, there's a wall about 3 feet to my right that the casings bounce off of.

 

[gobigkahuna]

I did a little experiment this morning. I moved the upper (plus BCA buffer and spring) to another lower that has a lighter trigger and hammer spring. I tried shooting 5 rounds of Federal (Hornady). It failed miserably. It would not cycle (I had one round that had the bullet pushed back into the casing, leaving powder all over the bench) and every casing was puffed. So I went back to the milspec lower (with BCA buffer and spring), shot another 5 rounds and it cycled perfectly. One out of 5 casings was puffed. Lesson learned, don't use a lighter hammer spring.

I also noticed that all my casings were ejected at roughly 90 degrees from the exit port.